diff --git a/mozilla/xpinstall/src/nsInstall.cpp b/mozilla/xpinstall/src/nsInstall.cpp
index fcc5e59bb16..fedb1d9913b 100644
--- a/mozilla/xpinstall/src/nsInstall.cpp
+++ b/mozilla/xpinstall/src/nsInstall.cpp
@@ -1834,11 +1834,23 @@ nsInstall::FileOpFileGetDiskSpaceAvailable(nsInstallFolder& aTarget, PRInt64* aR
 
 //nsIFileXXX: need to get nsIFile equivalent to GetModDate
 PRInt32
-nsInstall::FileOpFileGetModDate(nsInstallFolder& aTarget, nsFileSpec::TimeStamp* aReturn)
+nsInstall::FileOpFileGetModDate(nsInstallFolder& aTarget, double* aReturn)
 {
-  //nsCOMPtr<nsIFile> localFile = aTarget.GetFileSpec();
+    * aReturn = 0;
+
+    nsCOMPtr<nsIFile> localFile = aTarget.GetFileSpec();
+  
+    if (localFile)
+    {
+        double newStamp;
+        PRInt64 lastModDate = LL_ZERO;
+        localFile->GetLastModificationDate(&lastModDate);
+    
+        LL_L2D(newStamp, lastModDate);
+
+        *aReturn = newStamp;
+    }
 
-  //localFile->GetModDate(*aReturn);
   return NS_OK;
 }
 
@@ -1871,12 +1883,22 @@ nsInstall::FileOpFileIsFile(nsInstallFolder& aTarget, PRBool* aReturn)
 
 //nsIFileXXX: need to get the ModDateChanged equivalent for nsIFile
 PRInt32
-nsInstall::FileOpFileModDateChanged(nsInstallFolder& aTarget, nsFileSpec::TimeStamp& aOldStamp, PRBool* aReturn)
+nsInstall::FileOpFileModDateChanged(nsInstallFolder& aTarget, double aOldStamp, PRBool* aReturn)
 {
-  //nsFileSpec* localFS = aTarget.GetFileSpec();
+    *aReturn = PR_TRUE;
 
-  //*aReturn = localFS->ModDateChanged(aOldStamp);
-  return NS_OK;
+    nsCOMPtr<nsIFile> localFile = aTarget.GetFileSpec();
+    if (localFile)
+    {
+        double newStamp;
+        PRInt64 lastModDate = LL_ZERO;
+        localFile->GetLastModificationDate(&lastModDate);
+        
+        LL_L2D(newStamp, lastModDate);
+
+        *aReturn = !(newStamp == aOldStamp);
+    }
+    return NS_OK;
 }
 
 PRInt32
diff --git a/mozilla/xpinstall/src/nsInstall.h b/mozilla/xpinstall/src/nsInstall.h
index 720e2a03a8e..c4624a62450 100644
--- a/mozilla/xpinstall/src/nsInstall.h
+++ b/mozilla/xpinstall/src/nsInstall.h
@@ -243,11 +243,11 @@ class nsInstall
         PRInt32    FileOpFileExecute(nsInstallFolder& aTarget, nsString& aParams, PRInt32* aReturn);
         PRInt32    FileOpFileGetNativeVersion(nsInstallFolder& aTarget, nsString* aReturn);
         PRInt32    FileOpFileGetDiskSpaceAvailable(nsInstallFolder& aTarget, PRInt64* aReturn);
-        PRInt32    FileOpFileGetModDate(nsInstallFolder& aTarget, nsFileSpec::TimeStamp* aReturn);
+        PRInt32    FileOpFileGetModDate(nsInstallFolder& aTarget, double* aReturn);
         PRInt32    FileOpFileGetSize(nsInstallFolder& aTarget, PRInt64* aReturn);
         PRInt32    FileOpFileIsDirectory(nsInstallFolder& aTarget, PRBool* aReturn);
         PRInt32    FileOpFileIsFile(nsInstallFolder& aTarget, PRBool* aReturn);
-        PRInt32    FileOpFileModDateChanged(nsInstallFolder& aTarget, nsFileSpec::TimeStamp& aOldStamp, PRBool* aReturn);
+        PRInt32    FileOpFileModDateChanged(nsInstallFolder& aTarget, double aOldStamp, PRBool* aReturn);
         PRInt32    FileOpFileMove(nsInstallFolder& aSrc, nsInstallFolder& aTarget, PRInt32* aReturn);
         PRInt32    FileOpFileRename(nsInstallFolder& aSrc, nsString& aTarget, PRInt32* aReturn);
         PRInt32    FileOpFileWindowsShortcut(nsIFile* aTarget, nsIFile* aShortcutPath, nsString& aDescription, nsIFile* aWorkingPath, nsString& aParams, nsIFile* aIcon, PRInt32 aIconId, PRInt32* aReturn);
diff --git a/mozilla/xpinstall/src/nsJSFile.cpp b/mozilla/xpinstall/src/nsJSFile.cpp
index 5f9904d0313..df6f9b06c97 100644
--- a/mozilla/xpinstall/src/nsJSFile.cpp
+++ b/mozilla/xpinstall/src/nsJSFile.cpp
@@ -611,7 +611,7 @@ JSBool PR_CALLBACK
 InstallFileOpFileGetModDate(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
 {
   nsInstall*   nativeThis = (nsInstall*)JS_GetPrivate(cx, obj);
-  PRUint32     nativeRet;
+  double     nativeRet;
   JSObject *jsObj;
   nsInstallFolder *folder;
 
@@ -646,18 +646,7 @@ InstallFileOpFileGetModDate(JSContext *cx, JSObject *obj, uintN argc, jsval *arg
     return JS_TRUE;
   }
 
-  if ( nativeRet <= JSVAL_INT_MAX )
-    *rval = INT_TO_JSVAL(nativeRet);
-  else
-  {
-    JSInt64 l;
-    jsdouble d;
-
-    JSLL_UI2L( l, nativeRet );
-    JSLL_L2D( d, l );
-
-    JS_NewDoubleValue( cx, d, rval );
-  }
+  JS_NewDoubleValue( cx, nativeRet, rval );
 
   return JS_TRUE;
 }
@@ -814,7 +803,6 @@ InstallFileOpFileModDateChanged(JSContext *cx, JSObject *obj, uintN argc, jsval
 {
   nsInstall*   nativeThis = (nsInstall*)JS_GetPrivate(cx, obj);
   PRInt32      nativeRet;
-  PRUint32     b1;
   JSObject *jsObj;
   nsInstallFolder *folder;
 
@@ -831,7 +819,7 @@ InstallFileOpFileModDateChanged(JSContext *cx, JSObject *obj, uintN argc, jsval
     //  public int FileModDateChanged (nsInstallFolder aSourceFolder,
     //                                 Number aOldDate);
 
-    b1 = JSVAL_TO_INT(argv[1]);
+    jsdouble dval = *(JSVAL_TO_DOUBLE(argv[1]));
     if (argv[0] == JSVAL_NULL || !JSVAL_IS_OBJECT(argv[0])) //argv[0] MUST be a jsval
     {
       *rval =     *rval = BOOLEAN_TO_JSVAL(PR_FALSE);
@@ -848,7 +836,7 @@ InstallFileOpFileModDateChanged(JSContext *cx, JSObject *obj, uintN argc, jsval
 
     folder = (nsInstallFolder*)JS_GetPrivate(cx, jsObj);
 
-    if(!folder || NS_OK != nativeThis->FileOpFileModDateChanged(*folder, b1, &nativeRet))
+    if(!folder || NS_OK != nativeThis->FileOpFileModDateChanged(*folder, dval, &nativeRet))
     {
       return JS_TRUE;
     }